java – 让JLabel消失

这是我班级的架构.

摘要,GUI代码

abstract class Admin extends JFrame{
  protected static jlabel lbl_message= new jlabel("some text");
  // other functions and variables

  abstarct protected void performButtonClickAction();

}

用于实现抽象函数和提供其他功能的类.

final class AdminActionPerformer extends Admin{
  final public void performButtonClickAction(){
     // code for doin the task
     if(task is successful){
         new Thread(new Fader(Admin.lbl_message)).start();
     }
  }

 public static void main(String[] args) {
    new AdminActionPerformer().setVisible(true);
 }

}

使Jlabel后退的线程

class Fader implements Runnable{
  javax.swing.JLabel label;
  Color c;

  Fader(javax.swing.JLabel label){
    this.label=label;
    c=label.getBackground();
  }

  public void run() {
    int alpha=label.getGraphics().getColor().getAlpha()-5;
    while(alpha>0){
        System.out.println(alpha);
        alpha-=25;
        label.getGraphics().setColor(new Color(c.getRed(),c.getGreen(),c.getBlue(),alpha));
        label.repaint();
        try {
            Thread.sleep(50);
        } catch (InterruptedException ex) {
            Logger.getLogger(Fader.class.getName()).log(Level.SEVERE,null,ex);
        }
     }
  }
}

但标签并没有消失.我在这做错了什么？谢谢 ：)

附：我设置了JLabel opaque true.那是问题吗？我想最初显示带有背景颜色的标签,然后逐渐消失.